Why Apple Stock Fell So Far So Quickly

Apple's tumble back down from the stratosphere did some damage to the stock's other-worldly reputation but helped out some of its peers in the process.

Short-term market participants have been using the tech titan's shares in what are known as pair trades - betting that one stock will go higher while hedging that bet by short-selling a stock expected to go lower.

It's a strategy that has worked particularly well over the past five months as Apple's stock has crumbled while the rest of the market has surged higher. Anecdotal evidence from traders indicates that it's essentially an unraveling of the opposite trade that had been taking place prior to Apple's fall.

The pair trade also helps explain why Apple's fall from grace was so rapid and aggressive. (Read More: Sell-Off Costs Apple 'World's Most Valuable' Mantle)

"Apple is being used as a proxy in a lot of other things," said J.J. Kinahan, chief derivatives strategist at TD Ameritrade. "At least every other week you're either a buyer or seller of it, a lot of it depending on what the rest your stock (portfolio) is."

Traders in recent months have been mostly sellers of Apple, though shares did bounce back in Monday's stock market.

Shares surged as high as $705.07 back on Sept. 21 but have been in virtual freefall since the disappointing launch of the iPhone 5.

During that 36 percent slide traders have taken advantage, shorting the shares or selling them outright while going long other names in the industry.

Art Cashin, director of floor operations at UBS, said he has heard chatter of the pair trade that, while lacking specific data to back it up, "made for interesting cocktail speculation over the last few weeks."

Essentially the trade has worked like this: One side has used Apple as a stand-in for the computer and telecom industries, while the other component has used some of its direct and indirect competitors against Apple's direction.

Facebook, for one, has seen its shares surge after its disastrous initial public offering last spring while Apple has slumped.

Traders interviewed Monday pointed to a number of other companies that have benefited: Personal computer makers Dell and Hewlett-Packard, and smartphone competitors Research in Motion and Samsung, for instance. (Read More: Samsung Follows Apple Results With Record Profit)

Apple Store NYC
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Apple Store NYC

"Apple was in a league of its own. There was nothing that you traded against Apple," Kinahan said. "What this has done is made Apple just another stock - a great index stock of the tech industry. People can now use Apple in a pairs trade. Before, everyone was afraid to do it because Apple went straight up."

Yet the rebound Monday was a reminder that the company isn't going anywhere.

Instead, the relationship investors have with the stock may have changed for the long-term now that the meteoric rise appears to have run its course.

"Apple may become sort of a new-age value company for a while before the next great thing shows up, or if it shows up," said John Stoltzfus, chief market strategist at Oppenheimer. "In terms of whether Apple has seen its day as being a component of portfolios, it still has good upside potential. I don't think that era is over for it." (Read More: In Asia's Trend-Setting Cities, iPhone Fatigue Sets In)

The stock is heavily owned by mutual fund managers, with more than 1,000 having it as a top-10 component. Two-thirds of its shares are held by institutions.

So the drop from the September high could be at least in part due to simple portfolio rebalancing in which the stock more than tripled in value over a two-and-a-half year period.

Kinahan, of TD Ameritrade, said the shares could find support in the $425-$450 range, though they likely will remain a trading vehicle in lieu of another breakout.

"Apple now allows you to use it as a proxy for the tech industry overall in a way that's more affordable. The fear of the hyperbolic move to the upside has been taken away," he said. "So you're not going to have it go up $50 unexpectedly because the whole world is buying it for no apparent reason. It's trading for a reason now."